With the continued availability and accumulation of data in almost all fields, a growing need exists for data display systems that are capable of representing a substantial quantity of information in a readily perceivable form. Dynamic operation is important for such a system either to scan through data or to monitor real time data. The electroencephalogram (EEG) is exemplary of valuable data which is often ignored because traditionally it has not been available in a form that is readily perceivable. Specifically, the EEG is essentially a wave form that is representative of electrical variations occurring between distinct locations on the human head. The wave form depicts a non-periodic stochastic phenomenon. As is very well known in several fields of medicine, the EEG contains valuable data; however, the absence of recurring patterns in the wave form considerably complicates its analysis as for diagnostic use. Consequently, in the past the use of EEG has been relatively limited. In that regard, a significant advancement in creating a record of such data is disclosed in U.S. Patent Application Ser. No. 973,423, filed Dec. 26, 1978, and entitled APERIODIC ANALYSIS SYSTEM, AS FOR THE ELECTROENCEPHALOGRAM by Mihai C. Demetrescu, subsequently maturing into U.S. Pat. No. 4,215,697.
In the system of the referenced patent, the data of an aperiodic wave form is compacted to present a substantial interval of analog signal in a single picture. Essentially, as disclosed in detail in the patent, data is manifest to indicate characteristics of the EEG, which have come to be known in the field of EEG as waves (and spikes). Specifically, the amplitude of a wave of EEG, for example, is manifest as the height of a line or bar which appears in pictured three-dimensional coordinates. The three-dimensional coordinates may be indicated on a plane surface with the traditional format and symbols, X (horizontal), Y (vertical), and Z (depth). The amplitude of the wave is scaled to the vertical or Y coordinate, equivalent frequency (wave period) is indicated by horizontal displacement, and time is referenced to the depth or Z axis. By using such a format, several minutes of EEG recording can be represented on a single page.
While improved techniques for analyzing and displaying complex data as indicated above, have advanced the practicality of utilizing various data, e.g. EEG, a need has continued to exist for improving the display of the data in a perceivable form, particularly as in cases where real-time events are being monitored or a substantial period of data is to be progressively reviewed. That is, from a computer graphics point of view, a need has existed for an economic system to window complex data progressively, as with regard to time, so as to provide a dynamic display of selected data in a simple, perceivable form.
In general, the present invention is directed to a dynamic display system for presenting data as it is progressively windowed, for example, with reference to real time. Four dimensions (three spatial and one color) are defined by a reference field to graphically define data events on a two-dimensional surface as afforded by a television monitor. One of the spatial dimensions, for example, the depth or Z dimension of the reference field may be scaled to the independent variable, e.g., time, to accomplish a dynamic display, or progressively window select data.
A system of the present invention has been embodied to dynamically display EEG information in real time and with several minutes of data concurrently displayed. Waves of the EEG are presented as lines, the height (Y) of which are scaled to wave amplitude. The period of each wave (equivalent frequency) is indicated in a second spatial dimension (X), while time is indicated in a third dimension (Z). In the operating embodiment, time is progressive to develop the illusion of the data moving rearward along the line of perspective or Z dimension. Also, in the operating embodiment, color is utilized to stress the distinction between waves of different equivalent frequency ranges. The display is developed by a traditional television raster scan pattern which is critically oriented so that scanning lines conform to the symbol lines or bars to obtain clear definition.